java实现——030最小的k个数

1.O(nlogk)海量数据

 import java.util.TreeSet;
 
 public class T030 {
     public static void main(String[] args){
         int[] data = {4,5,1,6,2,7,3,8};
         TreeSet<Integer> leastNumbers = new TreeSet<Integer>();
         getLeastNumbers(data,leastNumbers,4);
 
     }
     public static void getLeastNumbers(int[] data,TreeSet<Integer> leastNumbers,int k){
         leastNumbers.clear();
         if(k<1||data.length<k)
             return;
 
         for(int i=0;i<data.length;i++){
             if(leastNumbers.size()<k)
                 leastNumbers.add(data[i]);
             else{
                 System.out.println(leastNumbers.last().hashCode());
                 if(data[i]<leastNumbers.last().hashCode()){
                     leastNumbers.remove(leastNumbers.last());
                     leastNumbers.add(data[i]);
                 }
 
             }
         }
         System.out.println(leastNumbers.toString());
     }
 }